QTH-locator - a system for approximate indication of the location of an object on the Earth's surface, adopted in amateur radio communications . Designed to determine the distance between correspondents. Also known as English. Grid Square Locator Maidenhead Locator System . The name comes from the QTH code expression , which means "I am in ...".
Modern QTH Locator Structure
The entire surface of the globe is divided into 324 sectors measuring 10 degrees latitude by 20 degrees longitude . Sectors are indicated by two capital Latin letters. Each sector is divided into 100 "large squares" measuring 1 degree of latitude by 2 degrees of longitude (approximately 78 × 111.4 km in the middle latitudes), they are indicated by two digits. The large square is divided into 576 "small squares" - 2.5 × 5 arc minutes (approximately 4.6 × 6.5 km), denoted by two lowercase Latin letters. If more accuracy is required, a small square can be divided into 100 even smaller ones, again denoted by numbers, and then in the same order. Naturally, we are not talking about squares in the geometric sense, at the poles the “squares" of the locator are completely triangular.
Thus, the coordinates, for example, Lobnya, Moscow region. accurate to a small square are written like this: KO86ra.
Radio amateurs often indicate their QTH locator on a QSL card or transmit it during a communication session , especially when they work not in the village, but in the field. Knowing the correspondent’s QTH locator is especially important in VHF radio communications, when the distance between the radio stations and the number of “squared” squares are taken into account when scoring.